Probably the fleece blankets which are made by cutting the edges into strips and tying them together. You can make the blanket two sided by using two different pieces of fabric, and tying those together.
The No Sew Blankets are blankets that are made of two separate fabrics that have been cut out. This kind of blanket does not require any sewing, you just need to tie the fabric using an overhand knot. You can get the instructions on how to make the No Sew Blanket at http://www.exploringwomanhood.com/homelife/ideas/pom-jan03.htm.